Question 1087553

{{{x^2 + 2x = 8}}}

{{{x^2 + 2x -8=0}}}...compare to {{{ax^2 + bx +c=0}}}, you see that {{{a=1}}}, {{{b=2}}}, and {{{c=-8}}}

{{{x = (-b +- sqrt( b^2-4*a*c ))/(2*a) }}} ....plug in {{{a=1}}}, {{{b=2}}}, and {{{c=-8}}}

{{{x = (-2 +- sqrt( 2^2-4*1*(-8) ))/(2*1) }}}

{{{x = (-2 +- sqrt(4+32 ))/2 }}}

{{{x = (-2 +- sqrt(36 ))/2 }}}

{{{x = (-2 +- 6)/2 }}}

solutions:

{{{x = (-2 + 6)/2 }}}=>{{{x = 2 }}}

{{{x = (-2 - 6)/2 }}}=>{{{x = -4 }}}